Higher amount deducted as debit order without my consent!

My husband and I have had a joint bond with Absa for years with a split debit order. On the 23rd of August 2018 I called to increase the debit order that is deducted from my account. When checking my statements it became apparent that not only have they continued to debit my husband of the original amount he agreed to, but they have deducted the full bond amount from my account. When I called in to correct this, I was informed that they no longer offer split debit orders and cannot rectify this. All they can do is delete one and the full amount must continue to come from one account. This is not what we agreed to. Strangely though, they have clearly continued to deduct a split amount yet will not rectify this to my original request. Instead I am offered an apology and the option of a refund. This is not enough. We agreed to this bond as we could split payment but to expect the full amount to come off of my account every month is ridiculous. We are very disappointed that after 45 minutes on the call, that still we sit with the full amount being deducted off of my account! Surely this is theft, I requested an additional amount and instead they have debited a higher amount without my consent to do so!